This document describes the methodology used by MLD staff to analyze
the mass of Dichotomous PM10 filter samples.

SUMMARY OF METHOD

Individual teflon filters (37 mm diameter) are weighed on an electronic
microbalance before and after field sampling. A sample consists of
a filter set, a coarse filter onto which 2.5 to 10 um particles are deposited,
and a fine filter that collects particles less than 2.5 um. Filter
weights are recorded directly employing a microbalance-computer interface
which then calculates the mass of particles per cubic meter of air (ug/m3).